minio/cmd/metacache-walk.go
Harshavardhana 66fcd02aa2
de-couple walkMu and walkReadMu for some granularity (#13231)
This commit brings two locks instead of single lock for
WalkDir() calls on top of c25816eabc.

The main reason is to avoid contention between readMetadata()
and ListDir() calls, ListDir() can take time on prefixes that
are huge for readdir() but this shouldn't end up blocking
all readMetadata() operations, this allows for more room for
I/O while not overly penalizing all listing operations.
2021-09-17 12:14:12 -07:00

363 lines
11 KiB
Go

// Copyright (c) 2015-2021 MinIO, Inc.
//
// This file is part of MinIO Object Storage stack
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
package cmd
import (
"context"
"io"
"net/http"
"net/url"
"sort"
"strconv"
"strings"
"github.com/gorilla/mux"
xhttp "github.com/minio/minio/internal/http"
xioutil "github.com/minio/minio/internal/ioutil"
"github.com/minio/minio/internal/logger"
)
// WalkDirOptions provides options for WalkDir operations.
type WalkDirOptions struct {
// Bucket to scanner
Bucket string
// Directory inside the bucket.
BaseDir string
// Do a full recursive scan.
Recursive bool
// ReportNotFound will return errFileNotFound if all disks reports the BaseDir cannot be found.
ReportNotFound bool
// FilterPrefix will only return results with given prefix within folder.
// Should never contain a slash.
FilterPrefix string
// ForwardTo will forward to the given object path.
ForwardTo string
}
// WalkDir will traverse a directory and return all entries found.
// On success a sorted meta cache stream will be returned.
// Metadata has data stripped, if any.
func (s *xlStorage) WalkDir(ctx context.Context, opts WalkDirOptions, wr io.Writer) (err error) {
// Verify if volume is valid and it exists.
volumeDir, err := s.getVolDir(opts.Bucket)
if err != nil {
return err
}
// Stat a volume entry.
if err = Access(volumeDir); err != nil {
if osIsNotExist(err) {
return errVolumeNotFound
} else if isSysErrIO(err) {
return errFaultyDisk
}
return err
}
// Use a small block size to start sending quickly
w := newMetacacheWriter(wr, 16<<10)
w.reuseBlocks = true // We are not sharing results, so reuse buffers.
defer w.Close()
out, err := w.stream()
if err != nil {
return err
}
defer close(out)
// Fast exit track to check if we are listing an object with
// a trailing slash, this will avoid to list the object content.
if HasSuffix(opts.BaseDir, SlashSeparator) {
metadata, err := s.readMetadata(pathJoin(volumeDir,
opts.BaseDir[:len(opts.BaseDir)-1]+globalDirSuffix,
xlStorageFormatFile))
if err == nil {
// if baseDir is already a directory object, consider it
// as part of the list call, this is a AWS S3 specific
// behavior.
out <- metaCacheEntry{
name: opts.BaseDir,
metadata: metadata,
}
} else {
st, sterr := Lstat(pathJoin(volumeDir, opts.BaseDir, xlStorageFormatFile))
if sterr == nil && st.Mode().IsRegular() {
return errFileNotFound
}
}
}
prefix := opts.FilterPrefix
var scanDir func(path string) error
scanDir = func(current string) error {
// Skip forward, if requested...
forward := ""
if len(opts.ForwardTo) > 0 && strings.HasPrefix(opts.ForwardTo, current) {
forward = strings.TrimPrefix(opts.ForwardTo, current)
if idx := strings.IndexByte(forward, '/'); idx > 0 {
forward = forward[:idx]
}
}
if contextCanceled(ctx) {
return ctx.Err()
}
s.walkMu.Lock()
entries, err := s.ListDir(ctx, opts.Bucket, current, -1)
s.walkMu.Unlock()
if err != nil {
// Folder could have gone away in-between
if err != errVolumeNotFound && err != errFileNotFound {
logger.LogIf(ctx, err)
}
if opts.ReportNotFound && err == errFileNotFound && current == opts.BaseDir {
return errFileNotFound
}
// Forward some errors?
return nil
}
if len(entries) == 0 {
return nil
}
dirObjects := make(map[string]struct{})
for i, entry := range entries {
if len(prefix) > 0 && !strings.HasPrefix(entry, prefix) {
// Do do not retain the file, since it doesn't
// match the prefix.
entries[i] = ""
continue
}
if len(forward) > 0 && entry < forward {
// Do do not retain the file, since its
// lexially smaller than 'forward'
entries[i] = ""
continue
}
if strings.HasSuffix(entry, slashSeparator) {
if strings.HasSuffix(entry, globalDirSuffixWithSlash) {
// Add without extension so it is sorted correctly.
entry = strings.TrimSuffix(entry, globalDirSuffixWithSlash) + slashSeparator
dirObjects[entry] = struct{}{}
entries[i] = entry
continue
}
// Trim slash, maybe compiler is clever?
entries[i] = entries[i][:len(entry)-1]
continue
}
// Do do not retain the file.
entries[i] = ""
if contextCanceled(ctx) {
return ctx.Err()
}
// If root was an object return it as such.
if HasSuffix(entry, xlStorageFormatFile) {
var meta metaCacheEntry
s.walkReadMu.Lock()
meta.metadata, err = s.readMetadata(pathJoin(volumeDir, current, entry))
s.walkReadMu.Unlock()
if err != nil {
logger.LogIf(ctx, err)
continue
}
meta.name = strings.TrimSuffix(entry, xlStorageFormatFile)
meta.name = strings.TrimSuffix(meta.name, SlashSeparator)
meta.name = pathJoin(current, meta.name)
meta.name = decodeDirObject(meta.name)
out <- meta
return nil
}
// Check legacy.
if HasSuffix(entry, xlStorageFormatFileV1) {
var meta metaCacheEntry
s.walkReadMu.Lock()
meta.metadata, err = xioutil.ReadFile(pathJoin(volumeDir, current, entry))
s.walkReadMu.Unlock()
if err != nil {
logger.LogIf(ctx, err)
continue
}
meta.name = strings.TrimSuffix(entry, xlStorageFormatFileV1)
meta.name = strings.TrimSuffix(meta.name, SlashSeparator)
meta.name = pathJoin(current, meta.name)
out <- meta
return nil
}
// Skip all other files.
}
// Process in sort order.
sort.Strings(entries)
dirStack := make([]string, 0, 5)
prefix = "" // Remove prefix after first level as we have already filtered the list.
if len(forward) > 0 {
idx := sort.SearchStrings(entries, forward)
if idx > 0 {
entries = entries[idx:]
}
}
for _, entry := range entries {
if entry == "" {
continue
}
if contextCanceled(ctx) {
return ctx.Err()
}
meta := metaCacheEntry{name: PathJoin(current, entry)}
// If directory entry on stack before this, pop it now.
for len(dirStack) > 0 && dirStack[len(dirStack)-1] < meta.name {
pop := dirStack[len(dirStack)-1]
out <- metaCacheEntry{name: pop}
if opts.Recursive {
// Scan folder we found. Should be in correct sort order where we are.
forward = ""
if len(opts.ForwardTo) > 0 && strings.HasPrefix(opts.ForwardTo, pop) {
forward = strings.TrimPrefix(opts.ForwardTo, pop)
}
logger.LogIf(ctx, scanDir(pop))
}
dirStack = dirStack[:len(dirStack)-1]
}
// All objects will be returned as directories, there has been no object check yet.
// Check it by attempting to read metadata.
_, isDirObj := dirObjects[entry]
if isDirObj {
meta.name = meta.name[:len(meta.name)-1] + globalDirSuffixWithSlash
}
s.walkReadMu.Lock()
meta.metadata, err = s.readMetadata(pathJoin(volumeDir, meta.name, xlStorageFormatFile))
s.walkReadMu.Unlock()
switch {
case err == nil:
// It was an object
if isDirObj {
meta.name = strings.TrimSuffix(meta.name, globalDirSuffixWithSlash) + slashSeparator
}
out <- meta
case osIsNotExist(err), isSysErrIsDir(err):
meta.metadata, err = xioutil.ReadFile(pathJoin(volumeDir, meta.name, xlStorageFormatFileV1))
if err == nil {
// It was an object
out <- meta
continue
}
// NOT an object, append to stack (with slash)
// If dirObject, but no metadata (which is unexpected) we skip it.
if !isDirObj {
if !isDirEmpty(pathJoin(volumeDir, meta.name+slashSeparator)) {
dirStack = append(dirStack, meta.name+slashSeparator)
}
}
case isSysErrNotDir(err):
// skip
default:
logger.LogIf(ctx, err)
}
}
// If directory entry left on stack, pop it now.
for len(dirStack) > 0 {
pop := dirStack[len(dirStack)-1]
out <- metaCacheEntry{name: pop}
if opts.Recursive {
// Scan folder we found. Should be in correct sort order where we are.
logger.LogIf(ctx, scanDir(pop))
}
dirStack = dirStack[:len(dirStack)-1]
}
return nil
}
// Stream output.
return scanDir(opts.BaseDir)
}
func (p *xlStorageDiskIDCheck) WalkDir(ctx context.Context, opts WalkDirOptions, wr io.Writer) error {
defer p.updateStorageMetrics(storageMetricWalkDir, opts.Bucket, opts.BaseDir)()
if err := p.checkDiskStale(); err != nil {
return err
}
return p.storage.WalkDir(ctx, opts, wr)
}
// WalkDir will traverse a directory and return all entries found.
// On success a meta cache stream will be returned, that should be closed when done.
func (client *storageRESTClient) WalkDir(ctx context.Context, opts WalkDirOptions, wr io.Writer) error {
values := make(url.Values)
values.Set(storageRESTVolume, opts.Bucket)
values.Set(storageRESTDirPath, opts.BaseDir)
values.Set(storageRESTRecursive, strconv.FormatBool(opts.Recursive))
values.Set(storageRESTReportNotFound, strconv.FormatBool(opts.ReportNotFound))
values.Set(storageRESTPrefixFilter, opts.FilterPrefix)
values.Set(storageRESTForwardFilter, opts.ForwardTo)
respBody, err := client.call(ctx, storageRESTMethodWalkDir, values, nil, -1)
if err != nil {
logger.LogIf(ctx, err)
return err
}
defer xhttp.DrainBody(respBody)
return waitForHTTPStream(respBody, wr)
}
// WalkDirHandler - remote caller to list files and folders in a requested directory path.
func (s *storageRESTServer) WalkDirHandler(w http.ResponseWriter, r *http.Request) {
if !s.IsValid(w, r) {
return
}
vars := mux.Vars(r)
volume := vars[storageRESTVolume]
dirPath := vars[storageRESTDirPath]
recursive, err := strconv.ParseBool(vars[storageRESTRecursive])
if err != nil {
s.writeErrorResponse(w, err)
return
}
var reportNotFound bool
if v := r.Form.Get(storageRESTReportNotFound); v != "" {
reportNotFound, err = strconv.ParseBool(v)
if err != nil {
s.writeErrorResponse(w, err)
return
}
}
prefix := r.Form.Get(storageRESTPrefixFilter)
forward := r.Form.Get(storageRESTForwardFilter)
writer := streamHTTPResponse(w)
writer.CloseWithError(s.storage.WalkDir(r.Context(), WalkDirOptions{
Bucket: volume,
BaseDir: dirPath,
Recursive: recursive,
ReportNotFound: reportNotFound,
FilterPrefix: prefix,
ForwardTo: forward,
}, writer))
}